1. Field of the Invention
The present invention relates to a high-frequency surgical treating device for use with an endoscope which is inserted through the endoscope into a body cavity of a human subject to incise a tissue region of, for example, the duodenal papillae.
2. Description of the Related Art
A high-frequency surgical knife for incising an affected region of a body cavity of a human subject with the use of a high-frequency current is known, for example, in Published Unexamined Japanese Utility Model 61-67710, DE-GM 8,709,823.7 and Published Unexamined Japanese Patent Application 63-255,050. In these cases, a conductive wire is inserted into a flexible sheath of electrically insulating property such that a wire portion somewhat short of its tip thereof is externally exposed at the distal end portion of the sheath. Upon the pull of the wire, the distal end portion of the sheath is curved.
A high-frequency incising area is provided at a straight cord portion of the exposed wire portion. The incising area is placed in contact with an affected region in a body cavity of a human being and, while being so done, a high-frequency current is flowed in the conductive wire to incise an affected tissue.
When an affected region in the body cavity of a human being is to be incised by this type of high-frequency surgical knife, various problems arise depending upon the situation under which it is involved.
In the case where the output of the biliary duct carrying bile into the duodena, for example, the duodinal papillae, is narrowed by the ulcer, etc., papillo-sphincterotomy (hereinafter referred to as an EST) is generally performed as a operation for incising some sphincter at the end of the biliary duct. If, upon carrying out an incising operation through the EST, some pancreas site is erroneously incised in the situation under which the blood vessels run in the neighborhood of a right side of a region to be incised, there occurs a hemorrhage or pancreatitis is liable to occur due to its hemorrhage.
In order to avoid the situation under which the pancreas site is wrongly incised in an attempt to incise a narrowed area of the duodenal pailae with the use of a high-frequency surgical knife, it is desired that, as viewing the distal end side of the sheath from the proximal (base) side of the sheath, the incising portion of the conductive wire of the high-frequency surgical knife be situated in the second quadrant area (hatched area) in a coordinate plane shown in FIG. 8.
The conventional high-frequency surgical knife, if being incorrectly used, will cause an unfavorable situation as set out below.
The high-frequency surgical knife as disclosed in Published Unexamined Japanese Utility Model 61-67710 is of such a type that the incising portion of the conductive wire incises an affected region 30 in the body cavity of a human subject at a positive side of a Y-axis on the coordinate plane shown in FIG. 8.
The high-frequency surgical knife of DE-GM 8,709,823.7 is of such a type that a stable sheet readily bendable toward a region to be incised is disposed within a sheath so as to provide a stabler bending characteristic to the knife as a whole and an incising operation is stably performed for an affected region 30 while the stable sheet is being positively bent toward the positive side of the Y-axis on the plane shown in FIG. 8.
However, these surgical knives, unless being manufactured with high accuracy, cannot perform an incising operation in a desired direction. Furthermore, the high-frequency incising area of the wire is readily liable to enter the first quadrant area from the Y-axis positive direction side. In order to avoid this situation, a high skill is required on the side of an operator.
In the high-frequency surgical knife of Published Unexamined Japanese Patent Application 63-255050, a coil-like shape memory alloy member is located in the distal end portion of the sheath and, upon being heated, takes on a circumferentially coiled form. If alignment fails to be obtained between the position of an incising area comprised of a conductive wire portion exposed on the outer periphery of the sheath and the position in which the affected region is to be incised, the shape memory alloy member is coiled by heat caused by electric current passed therethrough to turn or twist the distal end portion of the sheath. This, in turn, twists the incising area secured to the sheath to enable the direction of it to be aligned with the direction in which the affected region is to be incised.
In actual practice, it is difficult, however, to accurately control the degree of coiling of the shape memory alloy member. If the extent of coiling is too large, the surgical knife has to be drawn out of the endoscope and again inserted into it, requiring a lot of time. Furthermore, the high-frequency surgical knife becomes complicated in its construction and expensive.